The present invention relates to a process and device which make it possible to apply threads onto a support, particularly a support of plastic material or rubber, this process and device permitting, for instance, the production of reinforcement plies, in particular reinforcement plies for tires. The invention relates, in particular, to a process and device which permits the application of threads onto a support while imparting a sinuous shape to them.
Devices which permit the application of threads onto a support while imparting a sinuous shape to them are described, for instance, in the following patents or patent applications:
FR-A-2 042 859, FR-A-2 325 497, U.S. Pat. No. 1,800,179, U.S. Pat. No. 5,002,621, U.S. Pat. No. 4,820,143. PA1 complexity, giving rise to frequent failures, or requiring costly and frequent maintenance; PA1 lack of precision in the laying of the threads, so that the plies obtained have a heterogenous geometry and therefore have physical properties which vary along their length; PA1 slow speed. PA1 a) the thread is delivered with a controlled linear speed of value V.sub.1 ; PA1 b) the thread is displaced transversely to its direction of advance; PA1 c) it is applied onto the support, the thread having the sinuous shape as a result of the transverse displacement, the thread and the support thus in contact being driven in such a manner that the linear speed of the support has a value V.sub.2 which is less than V.sub.1 ; PA1 d) the conformation ratio of the thread thus applied onto the support is thus defined by the ratio V.sub.1 /V.sub.2. PA1 a) it has means making it possible to deliver the thread with a controlled linear speed of the value V.sub.1 ; PA1 b) it has means permitting the displacement of the thread transversely to its direction of advance; PA1 c) it has means making it possible to apply the thread onto the support, the thread having the sinuous shape due to the means which permit displacing it transversely, as well as means making it possible to drive the thread and the support thus in contact in such a manner that the linear speed of the support has a value V.sub.2 which is less than V.sub.1 ; PA1 d) the conformation ratio of the thread thus applied onto the support is thus defined by the ratio V.sub.1 /V.sub.2.
These devices have at least one of the following drawbacks:
U.S. Pat. No. 4,981,542 describes a device employing two clamps for applying yarns onto a support. This device makes it possible to deposit the threads with great precision, but the speed of deposition is relatively slow as a result of the complicated succession of movements of the clamps which require the stopping of the support upon the transverse movements of the threads before they are applied onto the support and upon the application of the threads onto the support.
U.S. Pat. No. 5,242,520 describes a device for applying threads on a support by means of a drum having fixed teeth and movable teeth, and U.S. Pat. No. 5,393,364 describes a device for applying threads on a support by feeding the threads with a controlled speed onto a drum, the sinuous form being obtained by means of teeth which are displaced with respect to the other teeth parallel to the axis of rotation, at least some of said teeth being flexible between a free end in contact with a thread and an anchoring zone. These devices make it possible to deposit the threads with great precision and with substantial speed, but they are relatively complicated and costly.